The question is, how likely is it that you or your son have been exposed to the virus? If either of you have it, your ex can contract it and bring it back to his parents as well.
It is best to talk to your doctor
, and then negotiate with your ex for the greater good of all involved. The wishes of the grandparents should also be considered. If they are otherwise in good health, the risk for serious complications is lowered significantly.
It's a difficult choice, but there are elderly members in my family who are not going to spend time with the grandkids or family who may have been exposed, for some time, because we live in an area with several dozen active cases.
A reminder, we all have opinions, but we are NOT a medical resource. Read more here: https://forums.livescience.com/thre...orums-are-not-medical-advice-or-counsel.1308/
Wishing you the best,